Effective sludge treatment is very important in a sewage treatment process. A sewage treatment plant usually reduces moisture content of the sludge from over 90% to between 60% and 80% by concentration and dehydration before implementing landfill, curing or drying treatment. Landfill tends to cause sludge fermentation, resulting in secondary environmental pollution. Existing curing or drying devices consume a large amount of energy in treating the sludge due to such characteristics of sludge as strong viscosity, aptness to cake, and hardness to disintegrate, and thus have difficulty in reducing cost and improving efficiency.
Chinese patent for invention CN101186422A provides a closed multi-chamber fluidized bed sludge drying method. The fluidized bed adopted in this method, which is energy-intensive and inefficient, has difficulty in carrying out continuous, large-scale sludge drying treatment.
The granted Chinese patent for utility model CN201000261Y, which was filed by the present applicant, provides a low-temperature sludge drying device. This drying device, while achieving drying of a certain amount of sludge, takes a long time. Hence, it consumes a great amount of energy and fails to realize the intended purpose of improving the drying efficiency.
Chinese patent for utility model CN203319838U provides a sludge curing treatment blender. The blender blends the sludge and an additive by mixing to cure the sludge. This process not only fails to remove moisture from the sludge but increases the volume of the sludge. And the cured sludge cannot be recycled.
Chinese Patent Application No. 201510006479.4 filed by the present applicant provides a bottom drying type sludge drying device, wherein as a stirring assembly in a first drying chamber stirs the sludge constantly, drying gas enters into a first drying chamber from a second drying chamber via a communication opening formed on a partition to dry the sludge piled on the partition. However, the sludge often clogs the communication opening during the sludge drying process. As a result, the drying gas has difficulty in entering into the first drying chamber smoothly via the communication opening, slowing down the sludge drying process.
Thus, there is a need for providing an improved bottom drying type drying device and a method to improve sludge drying efficiency.